Early childhood temperament, particularly behavioral inhibition, is seen as an expression of a child's biologically based negative reactivity to novelty and threat. Behavioral inhibited children have difficulty with peer interactions and exhibit withdrawal in novel social situations. Although expressed behavior may change with development, the underlying tendencies and general thresholds for attending to and reacting to novel or threatening stimuli in the environment may remain stable. These differences in reactivity may influence patterns of social competence particularly as individuals enter into periods of change and transition in their social contexts. . The period of young adulthood may be of particular importance in the lives of behaviorally inhibited individuals since it is marked by structural and cultural changes in the individual's social environment. This period also marks the peak for the emergence of anxiety disorders and substance use. Insofar as behavioral inhibition selectively influences the direction of attention to threat (i.e., anxiety) and the likelihood of engaging in substance use these individuals may be most at-risk for the development of maladaptive outcomes in young adulthood. We propose to study the mechanisms involving attention bias to threat and anticipation of reward and their role in the formation of personality and the emergence of psychopathology and substance use within a sample of 20-year-olds who were initially selected for differences in temperamental reactivity including behavioral inhibition. These subjects have been followed in a longitudinal study since they were four months of age. At multiple age points, measures of temperament, social behavior, physiological reactivity, and cognitive processing were obtained. The subjects in the current study will be seen for a two-day visit where they will be assessed for psychiatric status, and then presented with two different tasks during functional neuroimaging. The two tasks include assessment of their attention bias to threat and assessment of their reactivity to reward anticipation. We will also collect questionnaire data, via internet methods, on each subject and a peer nominated by the target subject. The goal is to identify developmental trajectories from early childhood temperament to psychiatric outcomes and substance use and examine the mediating effects of social competence and the moderating roles of attention to threat and reward processing. PUBLIC HEALTH RELEVANCE: The goal of this is to examine how the trajectories of childhood temperament predict the behavioral and neural correlates of attention bias to threat and incentive for reward in young adults with a history of behavioral inhibition, focusing specifically on the manner in which these processes moderate the association between temperament and anxiety disorders and substance use. Results from these studies will inform both prevention and intervention of anxiety disorders and associated substance use.